Pachymetry: Understanding Corneal Thickness Measurement

Pachymetry is a diagnostic test commonly used in ophthalmology

The goal of pachymetry is to measure corneal thickness. The cornea is the layer of transparent tissue that lines the anterior area of ​​the eye, and its usual thickness is between 500 and 600 microns in its central part, and between 600 and 800 in the peripheral zone. The thickness of the cornea is a variable to take into account during the diagnosis of diseases and for the performance of certain treatments.

How it is performed

The test is very simple to perform and does not cause any discomfort to the patient. Before carrying out the test, it must be taken into account to stop using contact lenses the days before (15 days if they are hard lenses and 5 to 8 days if they are soft).

There are currently three types of pachymetry:

• Optical Pachymetry, non-contact (difference between light reflections).
• Ultrasonic Pachymetry, of greater accuracy. It measures the corneal thickness using ultrasound at each point where the probe is placed.
• Coherence Laser Pachymetry (OCT), non-contact and highly accurate. In this case, pachymetry is integrated into which it allows us to determine various values ​​such as viewing images of the cornea as well as highly accurate measurements of corneal thickness (pachymetry).

To carry it out, a probe called pachymeter, which is placed in the front part of the eye (the cornea) to measure its thickness. The procedure is very fast, it does not take more than a few minutes. Previously, a local anesthetic is applied to the eye and the gaze must be kept fixed on a point while the data measured with the probe is recorded. It is done equally in both eyes.

Indications

It is indicated in the preoperative and follow-up of refractive surgery. In this type of surgery it is necessary for the patient to have a minimum thickness, since during the procedure its thickness is modified to correct It is also performed routinely in the diagnosis of other diseases, to see if there is inflammation (edema) corneal, thinning, as in the case of keratoconus and corneal dystrophies, in pre and post operative surgery for implantation of intrastromal rings, in follow-up glaucoma is used routinely.

What you should know:

• Test that usual to measure the thickness of the cornea.
• It is simple, it does not cause discomfort and it only requires you to stop using contact lenses a few days before.
• It helps in the diagnosis and treatment of certain diseases, and is used in the preoperative and follow-up of refractive surgery.

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